Method of coating lead sheathed cable



Jan. 15, 1946. T. K. cox ET AL METHOD OF COATING SHEATHED CABLE Original Filed Jun 30, 1942 3 Sheets-Sheet 1 Jan. E5, 194%, T. K. cox ETAL 2,393,024

METHOD OF COATING LEAD SHEATHED CABLE Original Filed June 30, 1942 5 Sheets-Sheet 2 lA/VEN was I A. Cox A. M GRA Y M A. RA YBUR/V Jan. 15, 1946. T. K. cox ETAL 23%,24

METHOD OF'COATING LEAD SHEATHED CABLE Original Filed June 30, 1942 3 Sheets-Sheet 3 Y VIA/E4.

Patented Jan. 15, 1946 2,393,024 METHOD OF COATING LEAD SHEATHED CABLE Thomas K. Cox, Randallstown, Alvin N. Gray, Joppa, and Vincent A. Rayburn, Baltimore. Md., assignors to Western Electric Company,

Incorporated, New York, N.

.of New York Y., a corporation Original application June 30, 1942, Serial No.- 449,070. Divided and this application May- 25. 1943, Serial No. 488,358

4 Claims. (01. 117-49) This invention relates to methods of coverin articles and more particularly to methods of covering cables or the like.

This application is a division of co-pending application, Serial No. 449,070, filed June 30, 1942.

It has been found highly desirable to coat leadsheathed communication cable with a rubber covering to prevent deterioration of the lead sheath due to the electrolytic action oi electric currents in and about the cable when the latter is buried in the ground. In order to obtain adhesion between the lead sheath and the rubber covering, one procedure has been to electroplate a thin coating of brass upon the lead sheath, to apply a layer of rubber compound thereover, and then to vulcanize the rubber compound. When this brass electroplating process is employed, surface irregularities or intervening foreign particles on the surface of the cable frequently cause arcing and spot fusing which may puncture the lead sheath.

Several organic compounds have been employed to cause rubber to adhere to a metal surface, but the usual practice is to coat a cold metal article with these fairly viscous, rubber adherent compounds and to dry the coating with external heat.

However, these organic compounds cannot be applied to a cold cable and dried by external heat with-sufllcient rapidity to make their use commercially practical.

It is highly desirable to apply a rubber adherent compound to a hot freshly extruded cable before the cable is reeled up, because grease must be applied to the cable just before it is reeled up to prevent adjacent coils of cable from sticking to one another. To later apply the rubber adherent compound to the cable would require the removal of the grease therefrom and the subsequent drying of the -cable surface. The difliculty encountered when these compounds are applied to a freshly extruded cable sheath is that the temperature of the lead sheath at that time is so high that rubber adherent organic compounds decompose and lose their adhesive properties when applied to the cable.

An object of this invention is to provide newand useful methods of covering articles and more particularly to provide new and useful methods of covering cables or the like.

An apparatus embodying the present invention comprises a plurality of atomizing nozzles positioned about the path of an article for projecting a finely divided spray of a cooling medium upon the article and a plurality of sprays for spraying upon the cable a liquid coating material, Cooling means are provided for cooling the coated cable.

Other'features and advantages of the invention will become apparent from the following detailed description of one embodiment thereof when read in conjunction with the accompanying drawings, in which Fig. 1 is a side elevation of an article treating apparatus;

Fig. 2 is a plan view of the article treating apparatus shown in Fig. 1; v V

Fig. 3 is an enlarged plan view of a portion of the article treating apparatusshown in Fig. 1;

Fig. 4 is a vertical sectional view taken on the line 4-4 of Fig. 3;

Fig. 5 is an enlarged vertical sectional view of a portion of the article'treatlng apparatus taken on the line 5-5 of Fig. 2;

Fig. 6 is an enlarged plan view of the apparatus shown in Fig. 5 taken on line 6-4 of Fig. l, and I Fig. 7 is an enlarged vertical cross-sectional view of the apparatus shown in Fig. 5 taken on the line 'I-l of Fig. l. I

In the particular embodiment of the invention disclosed in the accompanying drawings, a lead press Ill (Figs. 1 and 2) extrudes a sheath of lead at atemperature of approximately 450 F. about a cable core II to form the sheathed cable. Immediately after emerging from the lead press ill, the cable I2 is cooled by means of a cooling device, indicated in general at it (Fig. 1), which projects a mist of cooling medium upon the cable. The cooling device It, as shown in the enlarged views of Fig. 3 and Fig. 4, comprises three atomizing nozzles l5, l6 and I'I.- The upper two nozzles, l5 and II, are connected to a source l8 of air or other suitable gas through pipes l9 and 20 (Fig. 4), respectively, and to a source 2| of a cooling medium, such as water, through pipes 22 and 23 (Fig. 3), respectively; The lower nozzle I6 is connected to the air source l8 and to the water source 2| through the pipes 24 and 25 (Fig. 3), respectively. When the proper amounts of air and water are forced through the atomizing nozzles l5, l6 and II, a fine mist of atomized water particles are projected against and about the hot cable [2, those water particles which strike the cable flashing ofi immediately into steam.

.The nozzles i5, i6 and H and their piping connections are supported by lugs 26-26, which are affixed at one end to the pipes I9, 20, 2i and 22 and at the other end to sleeves 28-48 surrounding parallel rods 29-29. The rods 2929 and a rod 30 are bolted to a flat plate 3| having an aperture 32 (Fig. 4) formed therein to fit over die nut 34 of the lead press Ill. The rods 28-29 are connected at the other end to lugs "-38 which are welded to walls 38-38'formed in a sheet metal member 38. A threaded socket ll welded to the sheet metal member 39 near its lower extremity forms a junction for the rod 32.

A portion of the sheet metal member 39 is bent over to form a hook M (Fig. which extends over an edge 52 of a wall 43 of an exhaust duct 46 to support the cooling device It. Cable guide rings lt-flt are supported and positioned by means of arms 46- welded to the sleeves 28- 28, while a guide ring 41 is supported and positioned by means of arms 48-8-8 welded to the lugs 28-23.

The entire cooling device Il may be horizontally adjusted by' repositioning sleeves 63-63 upon the rods 23-29. For example the sleeves 88-83 at the right end of the device It, as seen in Fig. 3, may be removed, the sleeves 28-28 to which the lugs 28-28 are attached may be slid over the rods 29-28 toward the right and the sleeves 83-33 that were removed from the right end of the rods 28-25, may be slid on the left end or the rods 23-28. This manner of horizontally adjusting the cooling device M, permits rigid positioning of the cooling device and may be used to regulate to a certain extent the temperature of the cable as it passes into a container 89 between the walls 38-33. By disconnecting the the volatilized solvents, solvents having a high percentage of some non-inflammable solvent. such as carbon tetrachloride, may be employed. A particular thinner that has been found satis-. factory for thinning "Ty-Ply is composed of about 30% amyl-acetate and about 70% carbon tetrachloride.

The liquid coating material retained in the reservoir 60 passes through a strainer 65 to a centrifugal pump 32 which forces the liquid through the pipe to nozzles or sprays 65, 86-88 and 61-61. The pump 62 is preferably a glandless pump, because the carbon tetrachloride and other solvents in the coating material may destroy the oily material in the packing of a gland type pump and render it ineffective. The sprays 35, 83-88 and 81-67 are of the swirl type and project a finely divided spray of liquid coating material upon diiferent longitudinal parts of the cable (Fig. 5) and about various portions of the periphery thereof, as shown in Fig. '7. This particular arrangement of the sprays permits considerable freedom of movement of the cable to compenair and water pipes, the cooling device it may be removed from the rest of the apparatus merely by pushing the plate 3| forwardly off of the die nut 34, simultaneously freeing the hook 4| from the edge 42, and lifting the device It therefrom. In this manner repairs and replacements may be made with a minimum loss of time. Factors which may be regulated to control the tem- 1 perature of the cable as it enters the container 4-3 are the ratio of the amount of'water to the amount of air projected by the atomizers, the speed of the cable, and the thickness of the lead sheath.

The cable 12 isguided into and through the container "by means of a small guide sheave 50 and a large guide sheave ii. The guide sheave 50 has an axle 52 which is mounted in U-shaped slots 53-53 in support members 54-54 aflixed to the upper right hand portion of the container 18, as seen in Fig. 5. The cable l2 passes beneath the guide sheave 50 and over the guide sheave 5|. An axle 56 upon which the guide sheave 5| is mounted, is positioned in u-shaped slots 51-51 in support members 58-58, afllxed to the sides 58-58 of the container 39. .A reservoir 68, located in the lower portion of the container l8, retains a, supply of a liquid coating material, which in this particular embodiment of the invention is an organic, rubberadherent compound.

A particular rubber adherent compound that has been found satisfactory for the purposes of this invention is sold under the trade name Ty- Ply by R. T. Vanderbilt Company. Ty-Ply is a. dark, viscous liquid consisting essentially of a rubber hydrohalide, such as rubber hydrochloride, together .with a small amount of sulphur dispersed in a volatile vehicle, such as acetone, much in the same manner that a pigment is dispersed in a liquid vehicle to form a paint. Most compounds of this type are rather viscous liquids,

and must be thinned or out with a. suitable solvent or diluent to be applied satisfactorily by spraying. Solvents and diluents suitable for. cutting or thinning the rubber adherent compounds are generally quite volatile and inflammable. In order to lessen the explosion hazard produced by sate for sag and fleet between the guide sheave 5i and a take-up reel 15.

The temperature of the cable at the point at which the liquid coating material is applied is regulated by means of the cooling device l4 so as to-be low enough to prevent decomposition of the rubber adherent compound when applied to the cable surface, and high enough to quickly dry the liquid material upon the cable surface. For this purpose a temperature of about 250 F. has been found to be satisfactory. .When the temperature of the cable is correctly regulated, the liquid coating material willdry in a few seconds leaving a hard, non-tacky, metallic looking coating of the rubber adherent compound upon the surface of the cable ii. If the atomlzing nozzles are incorrectly adjusted and-the temperature at the point at which the coating material is applied is too high, a sizzling or frying of the liquid coating material upon the cable surface results. When this latter action occurs the rubber adherent compound is decomposed and is made ineffectual for causing the rubber covering to adhere to the lead sheath.

The excess coating material that is sprayed about the cable H and which does not adhere thereto is collected in the reservoir 68 and recirculated through the device. Since the vapors resulting from the volatilization of the solvent or diluent may be harmful to the operator and may create an explosion hazard, a number of vents 68-68 are disposed near the top of the container 43 which connect with an exhaust fan (not shown) through a chamber 63 which surrounds a portion of the container 49. A water jacket H surrounds the lower portion of the container and keeps the liquid coating material in the reservoir 88 cool to retard volatilization of the volatile constituents of the coating material.

After passing through the container 43, the

coated cable I2 is advanced through a trough I2 (Figs. 1 and 2) in which a plurality of vertical pipes 13-13 and horizontal pipes 14-" are disposed, each of which has a number of apertures formed therein to project jets of water upon the cable as it passes through the trough 12. Consequently the cable is relatively cool, approximately F. or lower, as it leaves the trough 12 and is wound upon a reel 15. The particular means used to cool the cable I I after it leaves the container 48 is of no importance, since any suitable means may be emplcyed by which the cable may be cooled sufficiently to prevent the rubber adherent compound from remaining sticky or gummy.

In operation a communication cable core H, or the like, is .passed through a lead press I wherein a lead sheath is extruded around the core. As the lead-sheathed cable leaves the lead press ID, the sheath has a temperature of approximately 450 F. At this temperature any of the organic rubber adherent compounds now in general use would be decomposed and made ineflective as adhesives. For this reason, the cable is cooled by projecting a mist of atomized water particles from the nozzles l5, l6 and I! thereabout. These minute water particles flash into steam the moment they strike the hot cable surface and cause rapid cooling of the cable, because these water particles have, in the aggreate, a very large surface area and consequently a very large amount of water contacts the cable. This fact combined with the fact that the evaporation of the water absorbs a large amount of heat accounts for the rapid cooling of the cable sheath by the atomized water particles. Since the atomized water particles flash off into steam immediately upon striking the cable surface, the cable sheath is never wetted with water. This last fact is important in the particular embodiment of the invention disclosed, since, if any moisture were left upon the cable surface, it would form a blister beneath the subsequently applied coating material and would cause peeling of the overlying'coating material.

It has been found desirable to reduce the temperature from about 450 R, which is the temperature at which the leadsheath is applied, to about 250 F. at the point at which the liquid coating material is applied. If the temperature is considerably above 250 F. decomposition of the organic rubber adherent compound may occur, while if the temperature is considerably below 250 F. the liquid coating material does not dry before it passes into the trough l2 and the coating is flushed off mechanically by the jets of cooling water.

After passing through the cooling device i 4, the cable I2 is guided into the container!!! by the small guide sheave 50 and over the large guide sheave 5|. The spray of coating material pro- J'ected by the nozzle'65 is the first to strike the hot cable l2 and is designed to hit it on its underside, since that side is the coolest becauseit has been in contact with the relatively cool sheave iii. The nozzles 66-66 are directed upon the cable l2 so as to coat the surface of the cable not coated by the spray ofcoating material pro- .iected from the nozzle 65. The spray from the nozzles 61-61 is so directed that it tends to produce a smooth coating upon the cable. As the coating material strikes the hot cable surface it solidifies to a certain extent immediately, and' within th space of a few seconds the volatile solvents or diluents are evaporated completely by the latent heat in the sheath, leaving a relatively hard coating upon the cable surface. The coated cable is passed through the trough 12 and cooled to about 150 F. by means of jets of water The thus coated cable may later be fed from the reel through an extrusion press and a layer of a rubber compound extruded thereabout.-

During the vulcanization of the rubber compound, the rubber is firmly bonded to the lead sheath by the rubber adherent compound. The device for extruding the rubber covering over the cable may be substituted for the trough 12, so that a rubber covering is applied to the coated cable immediately after the cable is coated.

Other modifications of the particular embodiment of the invention disclosed in the accompanying drawings will be apparent to those skilled in the art.

The invention comprises not only the treating of a lead-sheathed cable, but may be advantageously employed to treat other articles whenever it is desirable to coat the articles with a liq-1 uid coating material.

What is claimed is:

'1. The method of treating a hot, lead-sheathed cable, at least the sheath of which is at a temperature in excess of 250 R, which comprises projecting a fine mist of water about the cable to cool the sheath to a temperature of about 250" F., so regulating the mist of water that the Water is completely vaporized by the heat in the cable, spraying upon the cooled cable a liquid consisting essentially of a rubber hydrohalide, sulphur and a volatile diluent, and cooling the coated cable by projecting jets of water thereupon.

2. The method of treating a hot, lead-sheathed cable, at least the sheath of which is at a temperature above the boiling point of water, which comprises cooling the cable with an atomized spray of water which is so regulated that the water is instantaneously vaporized, spraying upon the cable a liquid immiscible with water consisting essentially of a rubber hydrohalide, sulphur Q and a volatile diluent, and drying the liquid upon the cable by means of the residual heat within the cable.

3. The methodof treating hot, lead-sheathed cables, at least the sheaths of which are at a temperature above the boiling point of water, which comprises cooling such a cable by projecting an atomized spray of water thereon, so regulating the spray that the water is completely vaporized by the heat in the cable, spraying upon the still warm cable a liquid coating material consisting essentially of a rubber hydrohalide, sulphur and a volatile diluent, drying the coating material upon the cable by means of the residual heat in the cable, and projecting jets of water upon the coated cable to cool it.

4. The method of coating hot, lead-sheathed cables, at least the sheaths of which are at a temperature above the boiling point of water, which comprises advancing such a cable through a mist of water to cool the cable, so regulating the speed of the cable and the mist of 'water that the cable is cooled to a predetermined temperature but all the water contacting the cable is vaporized, spraying upon the still warm cable a rubber adherent compound consisting essentially of rubber hydrochloride and a small amount of sulphur dispersed in a volatile diluent, drying the compound upon the cable by means of the residual heat in the cabl to form a coating upon the cable, and cooling the coating by projecting jets of water thereon.

THOMAS K. COX. ALVIN N. GRAY. VINCENT A. RAYBURN. 

